Heater



April 13, 1943. L. MEYER ETAL HEATER Filed Sept. 17, 1940 L I m w i 5/ mv0 0 a mZ/fi a M 2 Patented Apr. 13, 1943 2,316,273 imArEa Ludwig Meyerand Friedrich Klein, Dessau, Getmy; vested in the Alien PropertyCustodian Application September 17,1940, Serial No. 357,175

In Germany July 13,1939

4 Claims. (01. 257-441) This invention relates to improvements inheaters, and refers particularly to heaters primarily intended for useon airplanes.

Heaters operated by the heat generated by an engine'are in common use,and consist usually either of air heaters, or steam or hot waterheaters. Many heaters of the formertype are open to the grave objectionthat exhaust fumes are liable to mixwith and poison the air beingheated, which is particularly dangerous in airplane installations; andheaters of the latter type are not satisfactorycn airplanes for thereason that they are liable to freeze up.

It is an object of this invention to, provide a heater of the air typewherein the pipe through which the exhaust gases flow is spaced from thechamber through which the air to be heated passes by tubes through whichair also travels; and .to utilize these tubes as a. heat transfer mediumbetween the exhaust pipe and the air chamber so that a high ratio ofheat exchange is provided.

Another object of the invention is to provide such a heater centrallythrough which the exhaust pipe extends, and to provide anair cham heraround this pipe which is spaced therefrom by an annular arrangement oftubes 'so disposed that a plurality of connected walls extendcontinuously around the pipe and amply protect theair chamber fromcontamination by exhaust ases in the event even of cracking of the pipeitself.

A further :object of the invention is to provide such a heater whereinthe tubes, preferably rectangular in cross section, extend contiguous toone another parallel with the. exhaust pipe,

haust pipe preferably provided with a plurality of small indentations 20therein to increase its radiating capacity. Spaced concentrically aroundthe pipe is. is a second pipe 2! which forms the inner annular wall ofan air chamber i2-the outer encircling wall of which is shown at [2a.Closing the ends of the heater are two annular walls 18 the margins ofcentral openings of which are .brazed, welded or otherwise suitablysecured around the exhaust pipe 19: In this instance eachwall [8consists of two separate annular portions, the outer periphery of theinner portion being secured-tothe pipe 2i, and the outer sections I 8bbeing formed of flexed extremities of the outer chamber wall I2a.

' which are brazed or welded at their margins to the pipe 2|, as asafety precaution to prevent the entry of exhaust gases into the chamberi2; 2! denotes radiating fins which project part way across the chamberl2 from the pipe 2| which forms the inner wall of such chamber.

and are brazed or welded to the outer periphery of the latter, to theinner wall of the air chamber and to' one another, so that eiiicientheat transfer is obtained fromthe pipe to the cham ber,

Yet another object of the invention is to provide a heater which islight in weight, compact, efficient in operation, relatively easytomanufacture. and easy to install.

Having thus briefly enumerated some of the obiects and advanta es of theinvention, I will now proceed to describe a preferred embodimentthereof, with the aid of the accompanying drawing, in which: 1

Figure 1 illustrates a longitudinal section of the invention, and

Figure 2 is a section on the line 2-2 of Figure 1.

Referring to the drawing, is denotes an ex- A plurality of annularlyarranged spacing members or tubes 22, preferably substantiallyrectangular in cross section, extending parallel with the exhaust pipel9, have their adjacent walls brazed or welded to the latter, and theiropposite walls similarly secured to the pipe 2| which forms the innerwall of the chamber l2. The contiguous, substantially radial sides ofthe tubes 22 are also welded or brazed to one another throughout theirentire length, so that the tubes thus united to one another form anannular arrangement of radial walls between pipes I9 and 2| so thatshould'the former crack ample protection is afforded for preventingcontamination of the air flowing through the chamber I2 by the exhaustgases, and at the same time the sides or radial walls of the tubes 22constituteexcellent heat transfer means for the passage of heat from theexhaust pipe I 9 to the chamber i 2.

The tubes; 22 open at their extremities into an nular chambers 23a and-24a closed at their outer ends by the walls l8,'and projecting fromthese chambers and open to the outside air are pipes.

23 and 26 respectively. Connected to one exemity of the chamber I2 is anair inlet pipe 25. and projecting from its opposite extremity is asecond pipe 26 through which heated air flows to a suitable register oroutlet (not shown).

From the foregoing it will be clearly seen that hi h heat transfer isobtained from the exhaust p pe l9 to the air chamber I 2, mainly throughthe walls of the tubes 22; that the continuous annular arrangement ofthe connected tubes and th joints formed between them constituteadditional protection against leakage of gas from the pipe I! into thechamber l2; and that the end wall construction further assists inpreventing such leakage. Also that, due to the tubular construction ofthe heater, it is light in weight and therefore specially suited for usein airplanes.

While the preferred construction has been described and shown, it isunderstood that alterations and modifications may be made theretoprovided the said alterations and modifications fall within the scope ofthe appended claims.

What we claim is:

1. A heater comprising an annular chamber having an inlet and an outletpipe extending therefrom, an exhaust pipe projecting through the annularchamber and spaced therefrom, the chamber having annular end walls whichproject inwardly and are secured around the exhaust pipe, tubularspacing members annularly arranged around the exhaust pipe and welded orbrazed thereto and to said chamber, said spacing members beingcontiguous and brazed or welded to one another to form an encirclinggasproo'f joint between the exhaust pipe and chamber, said membersactingas a heat transfer medium between the exhaust pipe and thechember,and radiating-fins projecting partway across the interior of thechamber from its inner wall.

2. A heater comprising the combination set ing from the compartments topermit passage of air through said members.

3. A heater compriesing an annular air chamber having an inlet pipe andan outlet pipe connected thereto, an exhaust pipe extending through saidannular chamber, means directly connected to the exhaust pipe and theinner wall of the chamber spacing the exhaust pipe inwardly from thechamber comprising tub'ular spacing members of substantially rectangularcross section, the sides of contiguous members being secured to eachother throughout their height to form an encirclingv gasproof wallbetween the exhaust pipe and the chamber and to serve as means fortransferring heat from the exhaust pipe to the chamber.

4. A heater comprising an annular air chamber having an inlet pipe andan outlet pipe connected thereto, an exhaust pipe extending through saidannular chamber sealed therefrom and spaced from the inner wall thereofto provide an annular intermediate chamber, and

' spacing members directly connected to the exforth in claim 1, whereinthe spacing members' are substantially rectangular in cross section andterminate a short distance from both end walls thereby formingcompartments into which the tubes open, and pipes open to the airextendhaust pipe and to the inner wall of the chamber constituting heattransfer means from the former to the latter, said spacing memberscomprising a plurality of tubes annularly arranged around the exhaustpipe and having juxtaposed flat walls connected to one another to forman encircling gas-proof wall between the exhaust pipe and the chamber.

' LUDWIG MEYER.

FRIEDRICH KLEIN.

